Can someone explain after-market trading?

Doing some research, I see that the regular market trades between: 9:30 AM to 4:00 PM EST. pre-market trades between: 8AM to 9:30AM EST. And the after-hours market trades between: 4:30PM to 8PM EST

So does this mean I can trade anytime between 8 AM to 8 PM (EST)? What's the difference between pre and after market trades compared to regular market trading?

Submitted September 12, 2015 at 08:42PM by AppleDude13 http://ift.tt/1gixMfR